Active matrix programmable mirror

ABSTRACT

Microelectromechanical system (MEMS) devices, methods of operating the MEMS device, and methods of manufacturing the MEMS device are disclosed. In some embodiments, the MEMS device includes a glass substrate; an electrode on the glass substrate; a hinge mechanically coupled to the electrode; a membrane mirror mechanically coupled to the hinge; a TFT on the glass substrate and electrically coupled to the electrode; and a control circuit comprising: a multiplexer configured to turn on or turn off the TFT; and a drive source configured to provide a drive signal for charging the electrode through the TFT. An amplitude of the drive signal corresponds to an amount of charge, and the amount of charge generates an electrostatic force for actuating the hinge and a portion of the membrane mirror mechanically coupled to the hinge.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Application No.62/992,087, filed Mar. 19, 2020, the entire disclosure of which isherein incorporated by reference for all purposes.

FIELD OF INVENTION

This disclosure generally relates to microelectromechanical system(MEMS) devices. More specifically, this disclosure relates toelectrostatically actuated mirrors constructed using MEMS processes.

BACKGROUND OF THE INVENTION

Deformable mirrors (“DM”) include a reflecting surface whose topographycan be electronically programmed. DMs are critical in a wide variety ofoptical applications, including space-based telescopes.

Traditionally, the topography of the reflecting surface is controlled bya plurality of electrostrictive or electrostatic actuators. Theactuators are then combined with a mirror element to implement a DMfunction; in space-based telescopes, for example, sensitivityrequirements in instruments such as the coronagraph may be sensitive toresidual optical aberrations in the telescope mirrors, and the DM maycorrect for these errors. To reduce the cost of such systems, monolithicDMs have been designed and constructed using MEMS fabrication processes.These processes may include using silicon wafers as large as 200 mmdiameter, and large actuating arrays have been created using thisapproach.

A DM's performance may affect performance of an associated opticalsystem. Such systems may suffer from at least four deficiencies. First,a high voltage may be needed to actuate (e.g., a high voltage needed toactuate a stroke of 1 μm). For example, current devices may need 190V tomove the mirror surface 2 μm or 95V/μm. Second, each array element mayneed be addressed with its own control voltage, making the driveelectronics complex and expensive. For example, N² elements require N²wires and N² voltage sources. Third, each actuator is driven in the“voltage” mode, with a potentially short stroke range over which themirror can be stably controlled. Fourth, the mirror surfaces may exhibitunwanted topography and/or release etch holes, potentially causingproblems in high contrast instruments where scattered light needs to beminimized.

SUMMARY OF THE INVENTION

In some embodiments, a MEMS device including a DM is disclosed. In someembodiments, the MEMS device includes a glass substrate; an electrode onthe glass substrate; a hinge mechanically coupled to the electrode; amembrane mirror mechanically coupled to the hinge; a TFT on the glasssubstrate and electrically coupled to the electrode; and a controlcircuit comprising: a multiplexer configured to turn on or turn off theTFT; and a drive source configured to provide a drive signal forcharging the electrode through the TFT. An amplitude of the drive signalcorresponds to an amount of charge, and the amount of charge generatesan electrostatic force for actuating the hinge and a portion of themembrane mirror mechanically coupled to the hinge.

In some embodiments, a method of operating a MEMS device includes:measuring, through a glass substrate and an electrode, a gap between theelectrode and a portion of a membrane mirror; determining, based on themeasured gap, an amount of charge for generating an electrostatic forcefor actuating the portion of the membrane mirror; driving the electrodewith a drive signal having an amplitude to charge the electrode to theamount of charge; generating, with the amount of charge, theelectrostatic force; and actuating, using the electrostatic force, theportion of the membrane mirror.

In some embodiments, a method of manufacturing a MEMS device, includes:providing a glass substrate; depositing an electrode on the glasssubstrate; depositing a first sacrificial layer; forming a hinge,wherein the hinge is mechanically coupled to the electrode; depositing asecond sacrificial layer; depositing a membrane mirror above the secondsacrificial layer, wherein the membrane mirror is mechanically coupledto the hinge; and releasing the first and second sacrificial layers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B illustrate an exemplary MEMS device, according toembodiments of the disclosure.

FIG. 2 illustrates an exemplary MEMS device circuit, according toembodiments of the disclosure.

FIGS. 3A and 3B illustrate an exemplary MEMS device, according toembodiments of the disclosure.

FIGS. 4A-4G illustrate an exemplary manufacturing of an exemplary MEMSdevice, according to embodiments of the disclosure.

FIG. 5A illustrates an exemplary MEMS device, according to embodimentsof the disclosure.

FIG. 5B illustrates exemplary displacement of an exemplary MEMS device,according to embodiments of the disclosure.

FIG. 6 illustrates a method of operating an exemplary MEMS device,according to embodiments of the disclosure.

FIG. 7 illustrates a method of manufacturing an exemplary MEMS device,according to embodiments of the disclosure.

FIG. 8 illustrates a method of manufacturing an electromechanicalsystem, according to embodiments of the disclosure.

FIG. 9 illustrates an exemplary sensor, according to embodiments of thedisclosure.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

In the following description of embodiments, reference is made to theaccompanying drawings which form a part hereof, and in which it is shownby way of illustration specific embodiments which can be practiced. Itis to be understood that other embodiments can be used and structuralchanges can be made without departing from the scope of the disclosedembodiments.

FIG. 1A illustrates an exemplary MEMS device 100, according toembodiments of the disclosure. In some embodiments, the MEMS device 100is a DM device. In some embodiments, the MEMS device 100 includes amembrane mirror 102. In some embodiments, N×N actuators 104 (includingactuators 104A-104D) are located beneath the membrane mirror 102.

In some embodiments, N is 100, 64, 48, or 32. In some embodiments, N ismore than 100, up to 2000. In some embodiments, the MEMS device includesa rectangular actuator array grid with an actuator pitch of 50 μm to 500μm. Although a row of actuators having a specific arrangement are shown,it is understood that the MEMS device 100 includes actuators spanning aplane parallel to the mirror surface (e.g., N×N actuators are equallyspaced beneath the mirror surface), and that the MEMS device 100 mayinclude different actuator arrangements.

In some embodiments, a topography of the membrane mirror 102 iscontrolled by positions (e.g., height) of the actuators 104 (e.g., toachieve desired optical properties). For example, actuators 104B and104D are at a short height (e.g., corresponding to a first controlsignal level), actuator 104A and 104C are at a middle height (e.g.,corresponding to a second control signal level), and the rest of theactuators are at a tall height (e.g., corresponding to a third controlsignal level), forming the illustrated membrane mirror topography. Forexample, a charge level associated with the third control signal levelis higher than a charge level associated with a first control signallevel (e.g., more charge reduces a mirror gap more). In someembodiments, the DM update rate is 1 to 100 Hz (e.g., a rate of changeof the DM topography (e.g., by changing actuator heights)).

In some embodiments, the actuators 104 are pixel actuators, as describedin more detail herein. In some embodiments, as described in more detailherein, the height of the pixel actuator is electronically programmable,and the disclosed MEMS devices and methods of operating the MEMS devicesadvantageously allow the pixel actuators to be configured for longerstroke range (e.g., a range of programmable heights for an actuator)(e.g., three times the stroke range of present DMs) over which themirror can be stably controlled, compared to existing DM actuators. Insome embodiments, an actuator of the actuators 104 is configured for 1μm stroke range.

FIG. 1B illustrates an exemplary MEMS device 150, according toembodiments of the disclosure. In some embodiments, the MEMS device 150is a DM device. In some embodiments, the MEMS device 150 is the MEMSdevice 100. Although a two-by-two array of DM pixels (e.g., pixels156A-156D) is illustrated, it is understood that the MEMS device 150includes a suitable number of DM pixels to control a topography of amembrane mirror to meet system requirements. For example, the MEMSdevice 150 includes an N×N array of DM pixels (e.g., pixels 156A-156D).

In some embodiments, the MEMS device 150 includes a glass substrate 152.In some embodiments, a substrate of a disclosed MEMS device is atransparent substrate. In some embodiments, components of the MEMSdevice 150 are fabricated on the glass substrate 152. In someembodiments, the glass substrate 152 is fabricated using flat panelmanufacturing processes with low temperature polysilicon thin filmtransistor (LTPS TFT) capability. By fabricating the disclosed MEMSdevices on a glass substrate (e.g., a substrate that is at least 15times larger than a 200 mm silicon wafer) and leveraging lower costmanufacturing processes (e.g., compared to fabricating a device on asilicon wafer), larger and/or lower cost DMs may be possible. In someembodiments, disclosed MEMS devices reduce device cost by orders ofmagnitude. The larger and/or lower cost DMs may allow industries such asophthalmology, industrial lasers, and advanced node lithography (e.g.,EUV) to consider the disclosed DMs for optical solutions, which may bepossible for present hand assembled or non-multiplexed (e.g., which maynot be scalable and/or economical) DMs. In some embodiments, the LTPSTFT MEMS device may be more suitable than silicon-based MEMS devices forapplications where radiation hardening is required.

In some embodiments, the disclosed DM is used in space-based telescopes.In some embodiments, the disclosed DM is a device that can present ahighly precise reflecting surface across an aperture, and the topographyof the reflecting surface can be electronically programmed. In someembodiments, the programmed topography is used to compensate for certainoptical imperfections in an imaging instrument.

In some embodiments, the illustrated two-by-two array is a unit cell 154of an actuator array. For example, if the MEMS device 150 includes anN×N array of DM pixels, the MEMS device includes N/2×N/2 unit cells 154.In some embodiments, the unit cell 154 includes two-by-two pixels156A-156D. In some embodiments, the pixels 156A-156D are transparent(e.g., in the visible spectrum, in a particular spectrum) electrodes(e.g., indium tin oxide (ITO) electrodes, fluorine-doped tin oxide (FTO)electrodes, a ZnO electrode such as aluminum-doped zinc oxide (AZO)electrodes, indium-doped zinc oxide (IZO) electrodes, SnO₂ electrodes,In₂O₃ electrodes, Ag nanowire electrodes). In some embodiments, thepixels 156A-156D are not transparent electrodes. In some embodiments,the pixels 156A-156D are configured to allow radiation for measuring agap (e.g., a laser) between the pixel and the membrane mirror to pass.In some embodiments, the pixels are 50 μm to 500 μm apart. As describedin more detail herein, the transparent electrode, in concert with thetransparent glass substrate, may advantageously allow for laser probingfrom a backside (e.g., from a side of the glass substrate opposite tothe pixels) to measure or estimate an actuation gap associated with themembrane mirror topography. By being able to measure or estimate anactuation gap, an amount of desired charge to actuate the DM can becomputed, and the advantages associated with charge based actuation, asdescribed herein, may be possible.

In some embodiments, each of pixels 156A-156D corresponds to an actuator(e.g., actuators 104) for controlling a topography if the membranemirror 158 (e.g., membrane mirror 102). For example, each pixel is anactive electrode that imparts an electrostatic force (e.g.,electrostatic actuation) on a portion (e.g., a 400 μm by 400 μm portion,a 300 μm by 300 μm portion, a portion defined by a pixel pitch) of themembrane mirror 158 above the pixel.

In some embodiments, a thin film transistor (TFT) (e.g., TFTs 160A-160D)is electrically coupled to each pixel (e.g., TFT 160A is electricallycoupled to 156A, TFT 160B is electrically coupled to 156B, TFT 160C iselectrically coupled to 156C, TFT 160D is electrically coupled to 156D).In some embodiments, the TFTs 160A-160D are LTPS TFTs. In someembodiments, when the TFT is conducting (e.g., “on”), it is configuredallow charge to be transferred to a corresponding electrode (e.g.,provided by a corresponding drive signal (e.g., from column lines 164Aand 164B) to actuate a corresponding electrostatic actuator), and whenthe TFT is not conducting (e.g., “off”), it is configured toelectrically isolate the corresponding electrode from a correspondingdrive signal.

In some embodiments, row lines 162A and 162B are coupled to a first rowof TFTs (e.g., gates of TFTs 160A and 160C) and a second row of TFTs(e.g., gates of TFTs 160B and 160D), respectively. The signals on therow lines are configured to turn a corresponding row of TFTs on or off(e.g., to allow charge to be transferred to a corresponding row ofelectrode or to electrically isolate the corresponding row electrodefrom corresponding drive signals).

In some embodiments, column lines 164A and 164B are coupled to a firstcolumn of TFTs (e.g., sources or drains of TFTs 160A and 160B) and asecond column of TFTs (e.g., sources or drains of TFTs 160C and 160D),respectively. The drive signals on the column lines are configured tocontrol an actuation level of a corresponding electrostatic actuator.For example, the drive signal allows charge to be transferred to acorresponding electrode, and an amount of charge transferred to thecorresponding electrode (e.g., an actuator control signal) cause a levelof electrostatic actuator actuation (e.g., a level of actuation of acorresponding portion of the membrane mirror 158).

In some embodiments, the drive signals are provided by drive sources.For example, drive source 166A provides the drive signal for column line164A, and drive source 166B provides the drive signal for column line164B. In some embodiments, a drive source is configured to provide avoltage or a current for charging a corresponding electrode (e.g., togenerate an actuator control signal). In some embodiments, the drivesources are located off the glass substrate 152. In some embodiments,the drive sources are located on the glass substrate 152.

In some embodiments, the MEMS device 150 includes an opening 168 (e.g.,a hole). For example, each unit cell of the MEMS device 150 includes anopening 168. In some embodiments, the opening 168 is a hole in the glasssubstrate 152 (e.g., a MEMS release etch hole) that allows sacrificialmaterial above the glass substrate 152 to be etched from below (e.g.,with a suitable gas phase etchant). In some instances, the opening 168allows the top surface of the membrane mirror 158 to be continuous,advantageously reducing unwanted light scattering that may be present inexisting DMs (e.g., less than 0.5% potential light scattering for a 100μm by 100 μm pixel, to meet performing in scatter sensitive instrumentssuch as coronagraphs). In some embodiments, the opening 168 is createdby drilling (e.g., using a laser) the opening into the glass substrate152, by patterning lithographically, or etched, to provide releaseetchants to enter and escape the MEMS device. In some embodiments, theetching is performed by lithography and etch processes (e.g., with ahard mask).

In some embodiments, a disclosed opening or hole is a region in a glasssubstrate or a membrane mirror that does not include the glass substrateor the membrane mirror, but is surrounded by the glass substrate or themembrane mirror.

In some embodiments, the MEMS device 150 includes a MEMS hinge layer170. In some embodiments, the MEMS hinge layer 170 includes a hingemechanically coupled to a pixel or an electrode (e.g., a pixel of pixels156A-156D) and a corresponding portion of the membrane mirror 158 (e.g.,the hinge and the electrode do not necessarily overlap). In someexamples, a first component is mechanically coupled to a secondcomponent when the first component is actuated, the second component ismoved in response to the actuation. For example, when an electrode isbeing actuated, a hinge mechanically coupled to the electrode moves inresponse to the actuation, and a corresponding portion of the membranemirror is moved in response to the hinge moving (e.g., through adisclosed center post, through a direct mechanical connection betweenthe hinge and the membrane mirror).

In some embodiments, the MEMS hinge layer 170 is configured to supportthe membrane mirror 158 and provide a restoring force thatcounterbalances an attractive electrostatic force between an electrodeand a metal plane (e.g., a metal plane above the electrode). In someembodiments, the MEMS hinge layer 170 is fabricated using a MEMS process(e.g., deposition, photolithography, etch, and release; a MEMS processreferenced herein) with the hinge embedded in a suitable sacrificialmaterial that can be etched away, leaving behind a released hingestructure.

In some embodiments, the disclosed MEMS device is implemented usingmanufacturing technologies described in PCT PublicationPCT/US2019/022338 (IMG), the entire disclosure of which is hereinincorporated by reference for all purposes. IMG allows for theintegration of thin film transistor circuits and MEMS device features ona common glass substrate. In some embodiments, a hinge (e.g., of theMEMS hinge layer 170) disclosed herein is manufactured using themanufacturing technologies described in PCT PublicationPCT/US2019/022338.

In some embodiments, membrane mirror 158 is located above the MEMS hingelayer 170 (e.g., opposite from a direction from the hinge layer to thesubstrate). In some embodiments, the membrane mirror 158 is sufficientlythick (e.g., to reduce print-through of structures below the mirror).For example, the membrane mirror 158 is 1 μm thick. In some embodiment,the top surface of the membrane mirror 158 material is a reflectivemetal surface (e.g., aluminum, silver). In some embodiments, the metalsurface is dielectrically passivated to protect the surface and enhancereflectivity.

In some embodiments, the membrane mirror 158 includes a dielectriccenter sandwiched by metal layers. In some embodiments, a top or abottom metal layer of the membrane mirror 158 forms an interferometriccavity with a pixel, to allow optical readout of a gap between thebottom metal layer and the pixel, as described in more detail herein. Insome embodiments, a top metal layer of the membrane mirror is areflective material, as described herein, to support high efficiency andsystem power handling requirements.

In some embodiments, the hinges of the MEMS hinge layer 170 includerestoring springs (not shown). A suitable amount of restoring springsmay be included at appropriate locations of a disclosed MEMS device. Forexample, if restoring springs are included at intermediate locations(e.g., a spring having a different stiffness as a main spring, a springhaving a same stiffness as a main spring) between electrodes and atelectrode pitches, a full width half maximum (FWHM) of a correspondinginfluence function (e.g., displacement of a corresponding portion of themembrane mirror) for an actuated electrode is at a narrower width (e.g.,300 μm), allowing finer control of mirror topography. As anotherexample, if restoring springs are included at electrode pitches, FWHM ofa corresponding influence function for an actuated electrode is at awider width (e.g., 430 μm). In some embodiments, edges of an influencefunction of an electrode are affected by springs of neighboringelectrodes (e.g., for a rectangular electrode arrangement, a profilealong a diagonal would be different compare a profile along an axis; fora hexagonal electrode arrangement, profile along different axis of thehexagon would be more uniform).

In some embodiments, the disclosed DMs meet the following requirements:for a 64×64 actuator array and a 300 μm to 400 μm actuator pitch, a 6 nmRMS flattened surface is achieved. For a 32×32 actuator array, a 3 nmRMS flattened surface and a 8.5×10⁻⁹ coherent contrast at 10% bandwidthare achieved. For a 48×48 actuator array, less than 1×10⁻⁸ contrast isachieved. Contrast drifts of 1×10⁻¹² over 4 hours and 1×10⁻⁸ over 42hours are achieved. The drive electronics for the DM provide 16 bits orhigher resolution, contributing to a 1×10⁻¹⁰ contrast floor. In someembodiments, the disclosed DMs can achieve a stroke range of 1 μm with aresolution of 10 picometers (e.g., using the opticalestimation/measurement methods disclosed herein). In some embodiments,actuators of the disclosed DMs are configured for a longer stroke range(e.g., three times the stroke range of present DMs) over which themirror can be stably controlled.

FIG. 2 illustrates an exemplary MEMS device circuit 200, according toembodiments of the disclosure. In some embodiments, the MEMS devicecircuit 200 is part of a disclosed MEMS device. In some embodiments, theMEMS device circuit 200 is an addressing circuit for controllingelectrodes (e.g., pixels 156A-156D) for DM actuation. In someembodiments, the MEMS device circuit 200 implements a LTPS TFTaddressing mechanism for row-scanning the electrodes. The MEMS devicecircuit 200 advantageously reduces the complexity of the DM by reducinga number of required signals for controlling the electrostatic actuatorarray. For example, for a N×N array, using the disclosed pixel controlmultiplexing, the MEMS device circuit 200 reduce a number of requiredsignals for controlling the array to N, compared to N² in present DMs.

In some embodiments, the MEMS device circuit 200 includes pixels202A-202I, multiplexer 204, array driver 206, and transistors 208A-208I.For example, pixels 202A-202I include the pixels 156A-156D, andtransistors 208A-208I include TFTs 160A-160D. In some embodiments, themultiplexer 204 includes a shift register circuit that provides rowmultiplexing signal to select (e.g., by providing a suitable gatevoltage) one row (e.g., rows 212A-212C, which may include rows 162A and162B) after another in a sequence (e.g., and repeats after all the rowsof an array have been selected). In some embodiments, a frequency of therow scanning is 1 to 100 Hz.

In some embodiments, the array driver 206 provides drive signals forcolumns of the MEMS device circuit 200. For example, the columns210A-210C includes column lines 164A and 164B, and the array driver 206includes drive source 166A providing a drive signal for column line 164A(e.g., to charge a coupled electrode to achieve a desired electrostaticforce on a corresponding portion of the membrane mirror (e.g., membranemirror 158)) and drive source 166B providing a drive signal for columnline 164B (e.g., to charge a coupled electrode to achieve a desiredelectrostatic force on a corresponding portion of the membrane mirror(e.g., membrane mirror 158)). In some embodiments, the array driver 206is a part of a drive ASIC (e.g., a LCD column driver ASIC).

In some embodiments, the membrane mirror (e.g., membrane mirror 158) isconsidered to be a ground plane. For example, a bottom surface of themembrane mirror (e.g., a surface of the membrane mirror 158 facing theelectrodes, a conductive bottom mirror layer of the membrane layer, aconductive top mirror layer of the membrane layer) is the ground plane.In some embodiments, if a capacitance between an electrode and themirror ground plane is known, then a drive signal (e.g., a voltage, acurrent) applied to a column line can inject a desired amount of chargeto create a desired electrostatic force for a particular electrode (andcorresponding electrostatic actuator).

In some embodiments, the drive signal is a short voltage pulse ofamplitude V (e.g., less than 20V), and after the drive signal is appliedto the column line and a corresponding electrode, then a correspondingTFT is turned off (e.g., by multiplexer 204) to maintain the charge andelectrostatic force between the electrode and the mirror ground plane.In some embodiments, the amplitude V is less than voltages needed toactuate electrostatic actuators in voltage-controlled DMs, and thus,using the disclosed charge-controlled actuation advantageously savespower, compared to voltage-controlled DMs. For example, in someembodiments, low voltage (e.g., less than 10V) actuation isadvantageously provided by the disclosed charge-controlled pixelactuation.

For example, if the capacitance between the electrode and the mirrorground plane prior to actuation is C and the duration of the drivesignal (e.g., pulse width) (e.g., less than 10 μs) is much shorter thanmechanical response time of the mirror, then the charge injected intothe electrode is given by Q=CV. In some embodiments, C is estimated orcomputed by measuring a corresponding position of the membrane mirrorwith respect to the glass substrate (e.g., glass substrate 152).

For example, because the electrode and the glass substrate may betransparent, a laser beam incident from the substrate reflecting off themembrane mirror ground plane may be used to perform measurement with aninterferometer. In some examples, a fractional error in a capacitancemeasurement is equal to a fractional error in this measurement; if thereis an upper bound of 1 nm error associated with the laser measurement,then a low uncertainty of 1/1000 and 2 nm in actuation distanceadvantageously result, at a quiescent distance of 1 μm between theelectrode and the mirror ground plane.

As an exemplary advantage, using charge as the electrostatic actuationcontrol signal for electrostatic actuation, as described herein, may bemore stable and yield a longer stroke range than performingelectrostatic actuation using voltage because an actuation distance as afunction of charge is monotonic (e.g., it is not monotonic as a functionof voltage), and superposition of electrostatic forces may apply. Forexample, force, mirror gap, and charge may be expressed as

${F = {\frac{Q^{2}}{2\epsilon_{0}A} = {- {k\left( {x - x_{0}} \right)}}}},$

so the actuation distance as a function of charge may be expressed as

${x = {{- \frac{Q^{2}}{2\epsilon_{0}{Ak}}} + x_{0}}},$

where x₀ is an initial gap of a corresponding portion of the membranemirror. The transparent electrode and glass substrate of the disclosedMEMS devices advantageously allow the actuation distance to be measuredor estimated (e.g., using a laser) accurately, as explained above, andthus, the capacitance between an electrode and the mirror ground planecan be computed. By computing the capacitance between the electrode andthe mirror ground plane, a desired amount of charge and drive signalparameters (e.g., amplitude, pulse width) to achieve the desired amountof charge may be computed—allowing charge to be used as theelectrostatic actuation control signal for improved accuracy, improvedstability, improved topography smoothness (e.g., due to linearity ofcharge-controlled actuation), and/or longer stroke range (e.g., threetimes the stroke range, compared to using voltage) above using voltage.

As an example, at a first time, a first row of rows 212A-212C isselected by the multiplexer 204 by turning on the transistors of thefirst row. After the transistors of the first row are turned on, thearray driver 206 provides drive signals to the columns of the MEMSdevice circuit 200. In some embodiments, the array driver 206 is locatedoff the glass substrate (e.g., glass substrate 152). In someembodiments, the array driver 206 is located on the glass substrate(e.g., glass substrate 152). In some embodiments, a drive signal for acolumn is a signal (e.g., a voltage, a current) needed to charge acorresponding electrode on the selected row and the column (e.g.,coupled by a corresponding transistor) to achieve an electrostatic forceneeded to actuate a corresponding electrostatic actuator.

In this example, at a second time, after electrodes of the firstselected row are charged to a desired value (e.g., after the drivesignals are applied to electrodes of the first row), a second row ofrows 212A-212C, different from the first selected row, is selected bythe multiplexer 204 by turning on the transistors of the second row.After the transistors of the second row is turned on, the array driver206 provides drive signals to the columns of the MEMS device circuit200.

In some embodiments, all the rows of electrodes are charged in thismanner and a desired membrane mirror topography is achieved. In someembodiments, after a first desired membrane mirror topography isachieved, a second desired membrane mirror topography is programmed bydriving the electrodes in a similar manner with appropriate drive signalvalues to achieve desired electrostatic forces corresponding to thesecond desired topography.

FIGS. 3A and 3B illustrate an exemplary MEMS device 300, according toembodiments of the disclosure. In some embodiments, the MEMS device 300includes electrodes 302, mechanical hinges 304, and membrane mirror 306.In some embodiments, the MEMS device 300 is a part of the MEMS device150. For example, the electrodes 302 include transparent pixels156A-156D (e.g., transparent ITO electrodes) on a glass substrate,mechanical hinges 304 are part of the MEMS hinge layer 170, and membranemirror 306 is membrane mirror 158.

In some embodiments, the electrodes 302 have a pitch 308. In someembodiments, the pitch 308 is 50 μm to 500 μm. In some embodiments, asillustrated, the electrodes 302 are segmented into four quadrants. It isunderstood that the electrode 302 may be segmented differently toachieve desired properties and meet system requirements. It is alsounderstood that the electrode 302 may not be arranged in a rectangulargrid. For example, the electrode 302 may be arranged in a hexagonalgrid. In some embodiments, the electrodes 302 are segmented asillustrated to reduce tilting a corresponding portion of the membranemirror (e.g., due to asymmetries of an unsegmented electrode, chargedistribution on the unsegmented electrode may not be uniform) byallowing charge distribution the segmented electrode to be more uniform.

In some embodiments, a hinge 304 has a height 310 of 2 μm, and a centerpost 312 mechanically coupled to a hinge has a height 314 of 2 82 m. Insome embodiments, the hinges 304 and center posts 312 are aligned alongslots between electrode segments to reduce electrical shorting betweenelectrodes and the membrane mirror. In some embodiments, the hinges 304comprise silicon nitride, which has an intrinsic tensile stress toproduce a restoring force, when configured as a pair of crossedfixed-fixed beams, as illustrated.

The ratio of hinge stress to membrane mirror stress/drumhead stress maydetermine an extent of influence or shape function of the electrostaticactuators (e.g., corresponding to each electrode). For example, aninfluence function of one electrode is a Gaussian function with itsactuated peak (e.g., 1 μm) at a center point of the actuator and edgesof the electrode at half the peak value. As another example, aninfluence function of two neighboring electrostatic actuators has theiractuated peak (e.g., 1 μm) from a center point of a first electrode to acenter point of a second electrode and is at half the peak value an edgeof each of the electrodes. In some embodiments, the hinges areconfigured to be stronger, to more mechanically isolate between theelectrodes and allow for higher spatial frequencies (e.g., topographyreference rate). In some embodiments, the hinges are configured to beweaker, to allow for a smoother transition between adjacent portions ofa membrane mirror.

In some embodiments, the center post 312 is mechanically coupled betweenthe hinge 314 and the membrane mirror 306. In some embodiments, thecenter post 312 is constructed in a similar manner as the membranemirror 306 (e.g., the center post 312 is a same layer as a bottomsurface of the membrane mirror 306, as described with respect to FIGS.4A-4G), to smoothly diffuse the coupling between the center post and themembrane mirror (instead of creating a protusion).

In some embodiments, the electrodes 302 apply an electrostatic force tocorresponding portions of the membrane mirror to achieve a desiredtopography. For example, segments of an electrode 302 are driven at asame time by a drive signal to inject a same charge to the segments ofthe electrode and then electrically isolated from the drive signal by acorresponding TFT transistor or switch. When the electrode 302 iselectrically isolated from the drive signal, an electrostatic forceapplied to the membrane mirror 306 is constant and depends on the valueof the charge (e.g., the electrostatic actuation control signal)provided by the drive signal.

In some embodiments, the MEMS device 300 includes restoring springs (notshown) (e.g., a set of springs interspersed between main springs (e.g.,of the hinge) of the electrodes). A suitable amount of restoring springsmay be included at appropriate locations of a disclosed MEMS device. Forexample, if restoring springs are included at intermediate locationsbetween electrodes 302 and at electrode pitches, a full width halfmaximum (FWHM) of a corresponding influence function (e.g., displacementof a corresponding portion of the membrane mirror) for an actuatedelectrode is at a narrower width (e.g., 300 μm), allowing finer controlof mirror topography. As another example, if restoring springs areincluded only at electrode 302 pitches, FWHM of a correspondinginfluence function for an actuated electrode is at a wider width (e.g.,430 μm). In some embodiments, an attachment pad is coupled between themembrane mirror and a restoring spring. The FWHM may be widened bystiffening the attachment pad.

In some examples, due to influence of forces of neighboring electrodes,the force of the electrode may remain the same, even as a gap betweenthe electrode and the membrane mirror changes. Therefore, in theseexamples, superposition applies, and in some embodiments, a shape of themembrane mirror controlled by N×N electrodes can be calculated as alinear sum of individual forces, influences, or shape functions fromeach electrode, which is a simpler calculation compared tovoltage-controlled electrostatic actuators, where generated forces aremore complex non-linear functions of actuator positions (e.g., functionsthat include less regions of stability).

FIGS. 4A-4G illustrate an exemplary manufacturing of an exemplary MEMSdevice 400, according to embodiments of the disclosure. It is understoodthat a sequence of manufacturing the exemplary MEMS system may notfollow the sequence of FIGS. 4A-4G. For brevity, advantages of the MEMSdevice 400 described with respect to FIGS. 1-3 and 5 are not describedagain.

In some embodiments, as illustrated in FIG. 4A, a process ofmanufacturing an exemplary MEMS device (e.g., a MEMS device disclosedherein) begins with fabrication of a backplane 402 (e.g., LTPS TFTbackplane). In some embodiments, the backplane includes a glasssubstrate 404. For example, the backplane includes TFTs (e.g., electrodeor pixel switches), multiplexer (e.g., multiplexer 204), and routinglines for connecting the electrodes or pixels. In some embodiments, thebackplane is passivated by a layer of silicon dioxide 406. In someembodiments, transparent electrodes 408 (e.g., disclosed pixels orelectrodes) are deposited and connected to the backplane using vias. Insome embodiments, the backplane 402 provides interface requirements forthe electrodes 408.

In some embodiments, as illustrated in FIG. 4B, an opening 410 (e.g.,hole) is drilled. For example, the opening 410 is opening 168. In someembodiments, the opening 410 is drilled using laser drilling tools orpatterned lithographically, to fabricate a high aspect ratio opening inthe glass substrate 402.

In some embodiments, as illustrated in FIG. 4C, a first sacrificiallayer 412 backfilled the opening 410. In some embodiments, thesacrificial layer 412 includes a same sacrificial material used forformation of the MEMS device 400's electromechanical layer (e.g., hinges414).

In some embodiments, the first sacrificial layer 412 is a 2 μm thickpolyimide layer deposited over the electrodes 408. In some embodiments,the hinges 414 are silicon nitride hinges patterned on top of the firstsacrificial layer 412 and anchored to the glass substrate 404 usingvias. In some embodiments, a thickness of the hinges 414 is 200 nm.

In some embodiments, as illustrated in FIG. 4D, a second sacrificiallayer 416 is deposited over the hinges 414. In some embodiments, thesecond sacrificial layer 416 is a 2 μm thick polyimide layer. In someembodiments, vias for the center posts (e.g., above the hinges 414) arepatterned, and a bottom mirror layer 418 is deposited above the secondsacrificial layer 416 and into the center post vias. In someembodiments, the bottom mirror layer 418 is a 50 nm thick layer ofaluminum sputtered over the second sacrificial layer 416 and into thecenter post vias.

In some embodiments, as illustrated in FIG. 4E, a dielectric layer 420is deposited over the bottom mirror layer 418. In some embodiments, thedielectric layer 420 comprises a Spin-on-Dielectric (SOD) material(e.g., silicon dioxide particles suspended in a solution, which can becured to leave behind a flat solid layer, a material having a lowviscosity liquid state prior to curing and configured for planarizing)that is sufficiently thick to planarize the mirror topopgraphy (e.g., tocreate a flat top surface of the membrane mirror). In some embodiments,the dielectric layer 420 includes a series of SOD layers to meet morestringent flatness requirements. In some embodiments, as illustrated,the dielectric layer 420 fills center post areas of the bottom mirrorlayer 418. In some embodiments, the dielectric layer 420 is planarizedusing chemical mechanical polishing (CMP).

In some embodiments, a top mirror layer 422 is deposited above thedielectric layer 420 (e.g., to form a continuous mirror surface). Insome embodiments, the top mirror layer 422 is a 50-100 nm thickreflective material (e.g., aluminum) to meet reflectivity and systempower handling requirements. In some embodiments, the top mirror layer422 is planarized to create a flat mirror surface (e.g., to achieve aless than 5 nm RMS roughness).

In some embodiments, as illustrated in FIGS. 4F, material of the firstand second sacrificial layers 412 and 416 are removed. In someembodiments, the sacrificial layers are removed by oxygen plasma ashing.In some embodiments, if the opening 410 is plugged by a same material asthe first or second sacrificial layer, then the material in the opening410 is removed first, and a channel is formed for the plasma to ash thesacrificial material of the sacrificial layers.

In some embodiments, as illustrated in FIG. 4G, the MEMS device 400 isfabricated using the steps described with respect to FIGS. 4A-4F. Insome embodiments, the MEMS device 400 is formed after the sacrificialmaterial is ashed, and the opening 410 is subsequently plugged when theMEMS device 400 is packaged. In some embodiments, a membrane mirror ofthe MEMS device 400 includes the top mirror layer 422, the dielectriclayer 420, and bottom mirror layer 418. In some embodiments, a membranemirror of the MEMS device 400 includes the top mirror layer 422 and thedielectric layer 420. In some embodiments, protruding portions of thedielectric layer 420 and bottom mirror layer 418 form center posts ofthe MEMS device 400.

In some embodiments, after the MEMS device 400 formed in FIG. 4G, adriver chip (not shown) (e.g., drive sources 166A, 166B; array driver206) is attached to the glass substrate 404 (e.g., by anisotropicconductive film (ACF) bonding). In some embodiments, the driver chip ismounted on the glass substrate 404 (e.g., chip-on-glass). In someembodiments, the driver chip is mounted a flex cable (e.g.,chip-on-flex) that is bonded to the MEMS device.

FIG. 5A illustrates an exemplary MEMS device 500, according toembodiments of the disclosure. In some embodiments, as illustrated, theMEMS device 500 includes a 3×3 array of electrodes (e.g., an array ofthe disclosed electrodes) (not shown), corresponding mechanicalcomponents (e.g., hinges 502, center posts 504), and correspondingportion of the membrane mirror 506. In some embodiments, the hinges 502are tuned more stiffly, to reduce mechanical interactions betweenneighboring electrostatic actuators.

For example, as illustrated, a center electrode of the 3×3 array isbeing actuated. In some embodiments, a force applied by the centerelectrode is a charge-equivalent of 2 pC (e.g., 15V across a 150 fFcapacitor). The hinges 502 are 10 μm×200 nm silicon nitride with tensilestress of 100 MPa. The membrane mirror 506 is a 500 nm thick metallizedsilicon dioxide film with a tensile stress of less or equal 10 MPa,advantageously reducing energy required to actuate the membrane mirrorwhile meeting structural requirements. The shape of the membrane mirror506 may be determined from superposition of single-electrode shapefunctions.

In some embodiments, curve 508A of FIG. 5B shows displacement across amiddle portion (e.g., across a direction parallel to an axis of theelectrode array) of the membrane mirror 506 when center electrode of the3×3 array, with a pitch 512, being actuated and all electrodes of the3×3 array are mechanically coupled to hinges 502. Curve 508B of FIG. 5Bshows displacement across a diagonal portion (e.g., across a directiondiagonal to axes of the electrode array) of the membrane mirror 506 whencenter electrode of the 3×3 array being actuated and all electrodes ofthe 3×3 array are mechanically coupled to hinges 502.

In some embodiments, curve 510A of FIG. 5B shows displacement across amiddle portion of the membrane mirror 506 when center electrode of the3×3 array being actuated and only the center electrode of the 3×3 arrayis mechanically coupled to a hinge. Curve 510B of FIG. 5B showsdisplacement across a diagonal portion of the membrane mirror 506 whencenter electrode of the 3×3 array being actuated and only the centerelectrode of the 3×3 array is mechanically coupled to a hinge.

FIG. 6 illustrates a method 600 of operating an exemplary MEMS device,according to embodiments of the disclosure. In some embodiments, themethod 600 is performed with a system comprising a DM (e.g., MEMS device100, MEMS device 150, circuit 200, MEMS device 300, MEMS device 400,MEMS device 500). For the sake of brevity, some elements and advantagesassociated with these systems are not repeated here. Although the method600 is illustrated as including the described steps, it is understoodthat different order of step, additional step (e.g., combination withother methods disclosed herein), or less step may be included withoutdeparting from the scope of the disclosure.

In some embodiments, the method 600 includes measuring, through a glasssubstrate and an electrode, a gap between the electrode and a portion ofa membrane mirror (step 602). For example, as described with respect toFIGS. 1-5, a gap between a disclosed electrode and a disclosed membranemirror is measured. In some embodiment, the gap between the electrodeand the portion of the membrane mirror is measured using a laser throughthe glass substrate and the electrode.

In some embodiments, the method 600 includes determining, based on themeasured gap, an amount of charge for generating an electrostatic forcefor actuating the portion of the membrane mirror (step 604). Forexample, as described with respect to FIGS. 1-5, a topography of amembrane mirror and required electrostatic forces for generating thetopography are determined. Based on the measured gaps, amounts of charge(e.g., for each actuator) needed to generate the electrostatic forcesare determined to generate the topography.

In some embodiments, the method 600 includes driving the electrode witha drive signal having an amplitude to charge the electrode to the amountof charge (step 606). For example, as described with respect to FIGS.1-5, a disclosed drive source or array driver drives an electricallycoupled electrode with a drive signal having an amplitude (e.g., a shortvoltage pulse of amplitude V) to charge the electrode to the amount ofcharge (e.g., Q=CV, where C is the capacitance between the electrode andthe portion of the membrane mirror).

In some embodiments, the method 600 includes generating, with the amountof charge, the electrostatic force (step 608). For example, as describedwith respect to FIGS. 1-5, the charges on electrode generate anelectrostatic force on the portion of the membrane mirror.

In some embodiments, the method 600 includes actuating, using theelectrostatic force, the portion of the membrane mirror (step 610). Forexample, as described with respect to FIGS. 1-5, with the electrostaticforce generated by charges on the electrode, the portion of the membranemirror is actuated to generate a desired topography.

In some embodiments, the method 600 includes turning on a first TFT toelectrically couple the electrode to a first column line, whereindriving the electrode with the drive signal comprises driving the firstcolumn line with the drive signal; turning on a second TFT toelectrically couple a second electrode to a second column line; drivingthe second electrode with a second drive signal having a secondamplitude to charge the second electrode to a second amount of chargecomprising driving the second column line with the second drive signal;generating, with the second amount of charge, a second electrostaticforce; and actuating, using the second electrostatic force, a secondportion of the membrane mirror. In some embodiments, the first andsecond electrodes belong to a same row of electrodes. For example, asdescribed with respect to FIGS. 1-5, a first electrode and a secondelectrode of a same row are charged by a respective drive signal from arespective drive source.

In some embodiments, the method 600 includes turning on a first TFT toelectrically couple the electrode to a column line, wherein driving theelectrode with the first drive signal comprises driving the column linewith the first drive signal; turning off the first TFT to electricallyuncouple the first electrode from the column line; turning on a secondTFT to electrically couple a second electrode to the column line;driving the second electrode with a second drive signal having a secondamplitude to charge the second electrode to a second amount of chargecomprising driving the column line with the second drive signal;generating, with the second amount of charge, a second electrostaticforce; and actuating, using the second electrostatic force, a secondportion of the membrane mirror. For example, as described with respectto FIGS. 1-5, a first electrode and a second electrode of a same columnand different rows are scanned at different times and are charged by arespective drive signal at the different scanning times.

In some embodiments, the method 600 includes measuring, through theglass substrate and the electrode, a second gap between the electrodeand the portion of a membrane mirror, wherein the first electrostaticforce causes a gap between the electrode and the portion of the membranemirror to change from the first gap to the second gap; determining,based on the measured second gap, a second amount of charge forgenerating a second electrostatic force for actuating the portion of themembrane mirror; driving the electrode with a second drive signal havinga second amplitude to charge the electrode to the second amount ofcharge; generating, with the second amount of charge, the secondelectrostatic force; and actuating, using the second electrostaticforce, the portion of the membrane mirror. For example, as describedwith respect to FIGS. 1-5, at a subsequent cycle, the membrane mirror ismeasured again and a new electrostatic force is generated, as describedherein, to generate a second desired mirror topography.

In some embodiments, the method 600 includes measuring, through theglass substrate and a second electrode, a second gap between the secondelectrode and a second portion of the membrane mirror; determining,based on the measured second gap, a second amount of charge forgenerating a second electrostatic force for actuating the second portionof the membrane mirror; driving the second electrode with a second drivesignal having a second amplitude to charge the second electrode to thesecond amount of charge; generating, with the second amount of charge,the second electrostatic force; and actuating, using the secondelectrostatic force, the second portion of the membrane mirror. Forexample, as described with respect to FIGS. 1-5, at a subsequent cycle,the membrane mirror is measured at a second location and a secondelectrostatic force is generated, as described herein, to generate thedesired mirror topography.

FIG. 7 illustrates a method 700 of manufacturing an exemplary MEMSdevice, according to embodiments of the disclosure. In some embodiments,the method 700 is method of manufacturing a system comprising a DM(e.g., MEMS device 100, MEMS device 150, circuit 200, MEMS device 300,MEMS device 400, MEMS device 500). For the sake of brevity, someelements and advantages associated with these systems are not repeatedhere. Although the method 700 is illustrated as including the describedsteps, it is understood that different order of step, additional step(e.g., combination with other methods disclosed herein), or less stepmay be included without departing from the scope of the disclosure.

In some embodiments, the method 700 includes providing a glass substrate(step 702). For example, as described herein, a disclosed glasssubstrate is provided.

In some embodiments, the method 700 includes depositing an electrode onthe glass substrate (step 704). For example, as described with respectto FIGS. 1-5, a disclosed electrode is deposited on a disclosed glasssubstrate. In some embodiments, the electrode is a transparentelectrode.

In some embodiments, the method 700 includes depositing a firstsacrificial layer (step 706). For example, as described with respect toFIGS. 4A-4G, a first sacrificial layer 412 is deposited.

In some embodiments, the method 700 includes forming a hinge (step 708).For example, as described with respect to FIGS. 1-5, a disclosed hingeis formed. In some embodiments, the hinge is mechanically coupled to theelectrode.

In some embodiments, the method 700 includes depositing a secondsacrificial layer (step 710). For example, as described with respect toFIGS. 4A-4G, a second sacrificial layer 416 is deposited.

In some embodiments, the method 700 includes depositing a membranemirror above the second sacrificial layer (step 712). For example, asdescribed with respect to FIGS. 1-5, a disclosed membrane mirror isdeposited on a disclosed MEMS device. In some embodiments, the membranemirror is mechanically coupled to the hinge.

In some embodiments, the method 700 includes releasing the first andsecond sacrificial layers (step 714). For example, as described withrespect to FIGS. 4A-4G, the sacrificial layers are released.

In some embodiments, the method 700 includes creating openings in theglass substrate. For example, as described with respect to FIGS. 1-5, adisclosed opening or hole in a glass substrate is created. In someembodiments, releasing the first and second sacrificial layers comprisesreleasing the first and second sacrificial layers through the openings.For example, as described with respect to FIGS. 1-5, the first andsacrificial layers are released through a disclosed opening or hole in aglass substrate.

In some embodiments, the method 700 includes electrically coupling adriver chip to the MEMS device. For example, as described with respectto FIGS. 1-5, a drive chip (e.g., including circuit 200) is electricallycoupled to a disclosed MEMS device.

In some embodiments, the method 700 depositing the membrane mirrorincludes: depositing a bottom mirror layer; depositing a dielectriclayer; and depositing a top mirror layer. For example, as described withrespect to FIGS. 4A-4G, depositing the membrane mirror includesdepositing a bottom mirror layer 418, depositing a dielectric layer 420,and depositing a top mirror layer 422.

FIG. 8 illustrates a method 800 of manufacturing an electromechanicalsystem, in accordance with an embodiment. As non-limiting examples, theelectrochemical system could be associated with the devices (e.g., MEMSdevice 100, MEMS device 150, MEMS device 200, MEMS device 300, MEMSdevice 400, MEMS device 500) or systems described herein. To manufacturean electromechanical system, all or some of the process steps in method800 could be used and used in a different order. As a non-limitingexample, Step 814 could be performed before Step 812. In someembodiments, the method 600 or method 700 can be performed with method800.

Method 800 includes Step 802, providing a substrate. In someembodiments, the substrate is made of glass. In some embodiments, thesubstrate is low temperature polycrystalline silicon. In someembodiments, the substrate is a borosilicate that contains additionalelements to fine tune properties. An example of a borosilicate is byCorning Eagle™, which produces an alkaline earth boro aluminosilicate (asilicate loaded with boron, aluminum, and various alkaline earthelements). Other variations are available from Asahi Glass™ or Schott™.

In some embodiments, a flat panel glass process is used to manufacturethe electromechanical system. In some embodiments, a liquid crystaldisplay (LCD) process is used to manufacture the electromechanicalsystem. In some embodiments, an OLED display process or an x-ray panelprocess is used. Employing a flat panel glass process may allow forincreased substrate sizes, thereby allowing for a higher number ofelectrochemical systems per substrate, which reduces processing costs.Substrate sizes for “Panel Level” can include 620 mm×750 mm, 680 mm×880mm, 1100 mm×1300 mm, 1300 mm×1500 mm, 1500 mm×1850 mm, 1950 mm×2250 mm,and 2200 mm×2500 mm. Further, thin film transistors (TFTs) in panellevel manufacturing can also reduce cost and so, for example, LCD-TFTprocesses can be beneficial.

Method 800 includes Step 804, adding MEMS to the substrate. AlthoughMEMS is used to describe the addition of structures, it should beappreciated that other structures could be added without deviating fromthe scope of this disclosure. In embodiments using panel levelprocessing, the MEMS structures may be added using an LCD-TFT process.

Step 804 may be followed by optional Step 816, sub-plating. Step 816 maybe used when the substrate is larger than the processing equipment usedin subsequent steps. For example, if using a panel level process (suchas LCD), some embodiments will include (at Step 804) cutting the panelinto wafer sizes to perform further processing (using, for example, CMOSmanufacturing equipment). In other embodiments, the same size substrateis used throughout method 800 (i.e., Step 816 is not used).

Method 800 includes Step 806, releasing the MEMS from the substrate.

Method 800 includes Step 808, post-release processing. Such post-releaseprocessing may prepare the MEMS structure for further process steps,such as planarization. In wafer-level processing, planarization caninclude chemical mechanical planarization. In some embodiments, thefurther process steps include etch back, where a photoresist is spunonto the topography to generate a more planar surface, which is thenetched. Higher control of the etch time can yield a smoother surfaceprofile. In some embodiments, the further process steps include “spin onglass,” where glass-loaded organic binder is spun onto the topographyand the result is baked to drive off organic solvents, leaving behind asurface that is smoother.

Method 800 includes Step 810, vacuum encapsulation of the MEMSstructure, where necessary. Vacuum encapsulation may be beneficial toprolong device life.

Method 800 includes Step 812, singulation. Some embodiments may includecalibration and chip programming, which may take into account theproperties of the sensors. Methods described herein may be advantageousin glass substrate manufacturing processes because uniformity in glasslithography capabilities is limited. As a further advantage, glass has alower thermal conductivity and so a glass substrate can be a betterthermal insulator; by manufacturing thin structures separating abolometer pixel from a glass substrate, embodiments herein may betterserve to thermally isolate the glass bolometer pixel from the packagingenvironment.

Method 800 includes Step 814, attachment of a readout integrated circuit(ROIC) and flex/PCB attachment. As non-limiting examples, the readoutcircuits could be associated with devices or systems described herein.Processes and devices described herein may have the further advantagethat the area required for signal processing can be much smaller thanthe sensing area which is dictated by the sensing physics. Typically,sensors are integrated on top of CMOS circuitry, and area driven costslead to a technology node that is not optimal for the signal processingtask. Processes described herein can use a more suitable CMOS and drivedown the area required for signal processing, freeing the sensor fromany area constraints by leveraging the low cost of FPD (flat paneldisplay) manufacturing. In some embodiments, the ROIC is specificallydesigned for sensing a specific electromagnetic wavelength (such asX-Rays, THz, LWIR).

FIG. 9 illustrates an exemplary sensor. In some embodiments, sensor 900is manufactured using method 800. Sensor 900 includes glass substrate906, structure 904 less than 250 nm wide coupled to glass substrate 906,and a sensor pixel 902 coupled to the structure 904. In some embodimentsof sensor 900, structure 904 is a hinge that thermally separates theactive area from the glass. In some embodiments, sensor 900 receives aninput current or charge and outputs an output current or charge based onthe received radiation (e.g., the resistance between two terminals ofthe sensor changes in response to exposure to LWIR radiation).

In some embodiments, a sensor includes a glass substrate, a structuremanufactured from any of the methods described herein and coupled to theglass substrate, and a sensor pixel coupled to the structure.

In some embodiments, a sensor includes a MEMS or NEMS devicemanufactured by a LCD-TFT manufacturing process and a structuremanufactured by any of the methods described herein.

By way of examples, sensors can include resistive sensors and capacitivesensors. Bolometers can be used in a variety of applications. Forexample, long wave infra-red (LWIR, wavelength of approximately 8-14 μm)bolometers can be used in the automotive and commercial securityindustries. For example, LWIR bolometers with QVGA, VGA, and otherresolution. Terahertz (THz, wavelength of approximately 1.0-0.1 mm)bolometers can be used in security (e.g., airport passenger securityscreening) and medical (medical imaging). For example, THz bolometerswith QVGA resolution and other resolutions. Some electrochemical systemscan include X-Ray sensors or camera systems. Similarly, LWIR and THzsensors are used in camera systems. Some electromechanical systems areapplied in medical imaging, such as endoscopes and exoscopes. X-raysensors include direct and indirect sensing configurations.

Other electromechanical systems include scanners for light detection andranging (LIDAR) systems. For example, optical scanners where spatialproperties of a laser beam could be shaped (for, e.g., beam pointing).Electromechanical systems include inertial sensors (e.g., where theinput stimulus is linear or angular motion). Some systems may be used inbio sensing and bio therapeutic platforms (e.g., where biochemicalagents are detected).

In some embodiments, a non-transitory computer readable storage mediumstores one or more programs, and the one or more programs includesinstructions. When the instructions are executed by an electronic device(e.g., MEMS device 100, MEMS device 150, MEMS device 200, MEMS device300, MEMS device 400, MEMS device 500) with one or more processors andmemory, the instructions cause the electronic device to perform themethods described with respect to FIGS. 1A, 1B, 2, 3A, 3B, 5A, 5B, and6.

Although “electrically coupled” and “coupled” are used to describe theelectrical connections between two electronic components or elements inthis disclosure, it is understood that the electrical connections do notnecessarily need direct connection between the terminals of thecomponents or elements being coupled together. For example, electricalrouting connects between the terminals of the components or elementsbeing electrically coupled together. In another example, a closed(conducting or an “on”) switch is connected between the terminals of thecomponents being coupled together. In yet another example, additionalelements connect between the terminals of the components being coupledtogether without affecting the characteristics of the circuit. Forexample, buffers, amplifiers, and passive circuit elements can be addedbetween components or elements being coupled together without affectingthe characteristics of the disclosed circuits and departing from thescope of this disclosure.

In one aspect, a MEMS device includes a glass substrate; an electrode onthe glass substrate; a hinge mechanically coupled to the electrode; amembrane mirror mechanically coupled to the hinge; a TFT on the glasssubstrate and electrically coupled to the electrode; and a controlcircuit comprising: a multiplexer configured to turn on or turn off theTFT; and a drive source configured to provide a drive signal forcharging the electrode through the TFT. An amplitude of the drive signalcorresponds to an amount of charge, and the amount of charge generatesan electrostatic force for actuating the hinge and a portion of themembrane mirror mechanically coupled to the hinge.

In one aspect, a method of operating a MEMS device includes: measuring,through a glass substrate and an electrode, a gap between the electrodeand a portion of a membrane mirror; determining, based on the measuredgap, an amount of charge for generating an electrostatic force foractuating the portion of the membrane mirror; driving the electrode witha drive signal having an amplitude to charge the electrode to the amountof charge; generating, with the amount of charge, the electrostaticforce; and actuating, using the electrostatic force, the portion of themembrane mirror.

In one aspect, a method of manufacturing a MEMS device, includes:providing a glass substrate; depositing an electrode on the glasssubstrate; depositing a first sacrificial layer; forming a hinge,wherein the hinge is mechanically coupled to the electrode; depositing asecond sacrificial layer; depositing a membrane mirror above the secondsacrificial layer, wherein the membrane mirror is mechanically coupledto the hinge; and releasing the first and second sacrificial layers.

Those skilled in the art will recognize that the systems describedherein are representative, and deviations from the explicilty disclosedembodiments are within the scope of the disclosure. For example, someembodiments include additional sensors or cameras, such as camerascovering other parts of the electromagnetic spectrum, can be devisedusing the same principles.

Although the disclosed embodiments have been fully described withreference to the accompanying drawings, it is to be noted that variouschanges and modifications will become apparent to those skilled in theart. Such changes and modifications are to be understood as beingincluded within the scope of the disclosed embodiments as defined by theappended claims.

The terminology used in the description of the various describedembodiments herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used in thedescription of the various described embodiments and the appendedclaims, the singular forms “a”, “an,” and “the” are intended to includethe plural forms as well, unless the context clearly indicatesotherwise. It will also be understood that the term “and/or” as usedherein refers to and encompasses any and all possible combinations ofone or more of the associated listed items. It will be furtherunderstood that the terms “includes,” “including,” “comprises,” and/or“comprising,” when used in this specification, specify the presence ofstated features, integers, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, integers, steps, operations, elements, components,and/or groups thereof.

We claim:
 1. A microelectromechanical system (MEMS) device, comprising:a glass substrate; an electrode on the glass substrate; a hingemechanically coupled to the electrode; a membrane mirror mechanicallycoupled to the hinge; a TFT on the glass substrate and electricallycoupled to the electrode; and a control circuit comprising: amultiplexer configured to turn on or turn off the TFT; and a drivesource configured to provide a drive signal for charging the electrodethrough the TFT, wherein: an amplitude of the drive signal correspondsto an amount of charge, and the amount of charge generates anelectrostatic force for actuating the hinge and a portion of themembrane mirror mechanically coupled to the hinge.
 2. The MEMS device ofclaim 1, further comprising an opening in the glass substrate.
 3. TheMEMS device of claim 1, wherein: a gap between the electrode and theportion of the membrane mirror is a function of a charge on theelectrode, and the MEMS device is configured to measure the gap throughthe glass substrate and electrode.
 4. The MEMS device of claim 1,wherein: the first TFT is electrically coupled to a first row line and acolumn line, and the multiplexer is configured to turn on or turn offthe first TFT through the first row line, and the drive source isconfigured to provide the first drive signal for charging the firstelectrode through the column line, the device further comprising: asecond electrode on the glass substrate; and a second TFT on the glasssubstrate and electrically coupled to the second electrode, a second rowline, and the column line, wherein: the multiplexer is furtherconfigured to: turn on or turn off the second TFT through the second rowline; and turn on the second TFT when the first TFT is off, the drivesource is configured to provide a second drive signal for charging thesecond electrode through the column line and the second TFT, anamplitude of the second drive signal corresponds to a second amount ofcharge, and the second amount of charge generates a second electrostaticforce for actuating a second portion of the membrane mirror.
 5. The MEMSdevice of claim 1, wherein: the first TFT is electrically coupled to arow line and a first column line, and the multiplexer is configured toturn on or turn off the first TFT through the row line, and the drivesource is configured to provide the first drive signal for charging thefirst electrode through the first column line, the device furthercomprising: a second electrode on the glass substrate; a second TFT onthe glass substrate and electrically coupled to the second electrode,the row line, and a second column line; and a second drive sourceconfigured to provide a second drive signal for charging the secondelectrode through the second column line and the second TFT, wherein: anamplitude of the second drive signal corresponds to a second amount ofcharge, and the second amount of charge generates a second electrostaticforce for actuating a second portion of the membrane mirror.
 6. The MEMSdevice of claim 1, wherein the electrode is segmented.
 7. The MEMSdevice of claim 1, further comprising a restoring spring mechanicallycoupled to the membrane mirror.
 8. The MEMS device of claim 1, furthercomprising a center post mechanically coupled to the hinge and themembrane mirror.
 9. The MEMS device of claim 1, wherein the electrode isa transparent electrode.
 10. A method of operating a MEMS device,comprising: measuring, through a glass substrate and an electrode, a gapbetween the electrode and a portion of a membrane mirror; determining,based on the measured gap, an amount of charge for generating anelectrostatic force for actuating the portion of the membrane mirror;driving the electrode with a drive signal having an amplitude to chargethe electrode to the amount of charge; generating, with the amount ofcharge, the electrostatic force; and actuating, using the electrostaticforce, the portion of the membrane mirror.
 11. The method of claim 10,wherein the gap between the electrode and the portion of the membranemirror is measured using a laser through the glass substrate and theelectrode.
 12. The method of claim 10, further comprising: turning on afirst TFT to electrically couple the electrode to a first column line,wherein driving the electrode with the drive signal comprises drivingthe first column line with the drive signal; turning on a second TFT toelectrically couple a second electrode to a second column line; drivingthe second electrode with a second drive signal having a secondamplitude to charge the second electrode to a second amount of chargecomprising driving the second column line with the second drive signal;generating, with the second amount of charge, a second electrostaticforce; and actuating, using the second electrostatic force, a secondportion of the membrane mirror, wherein the first and second electrodesbelong to a same row of electrodes.
 13. The method of claim 10, furthercomprising: turning on a first TFT to electrically couple the electrodeto a column line, wherein driving the electrode with the first drivesignal comprises driving the column line with the first drive signal;turning off the first TFT to electrically uncouple the first electrodefrom the column line; turning on a second TFT to electrically couple asecond electrode to the column line; driving the second electrode with asecond drive signal having a second amplitude to charge the secondelectrode to a second amount of charge comprising driving the columnline with the second drive signal; generating, with the second amount ofcharge, a second electrostatic force; and actuating, using the secondelectrostatic force, a second portion of the membrane mirror.
 14. Themethod of claim 10, further comprising: measuring, through the glasssubstrate and the electrode, a second gap between the electrode and theportion of a membrane mirror, wherein the first electrostatic forcecauses a gap between the electrode and the portion of the membranemirror to change from the first gap to the second gap; determining,based on the measured second gap, a second amount of charge forgenerating a second electrostatic force for actuating the portion of themembrane mirror; driving the electrode with a second drive signal havinga second amplitude to charge the electrode to the second amount ofcharge; generating, with the second amount of charge, the secondelectrostatic force; and actuating, using the second electrostaticforce, the portion of the membrane mirror.
 15. The method of claim 10,further comprising: measuring, through the glass substrate and a secondelectrode, a second gap between the second electrode and a secondportion of the membrane mirror; determining, based on the measuredsecond gap, a second amount of charge for generating a secondelectrostatic force for actuating the second portion of the membranemirror; driving the second electrode with a second drive signal having asecond amplitude to charge the second electrode to the second amount ofcharge; generating, with the second amount of charge, the secondelectrostatic force; and actuating, using the second electrostaticforce, the second portion of the membrane mirror.
 16. A method ofmanufacturing a MEMS device, comprising: providing a glass substrate;depositing an electrode on the glass substrate; depositing a firstsacrificial layer; forming a hinge, wherein the hinge is mechanicallycoupled to the electrode; depositing a second sacrificial layer;depositing a membrane mirror above the second sacrificial layer, whereinthe membrane mirror is mechanically coupled to the hinge; and releasingthe first and second sacrificial layers.
 17. The method of claim 16,further comprising electrically coupling a driver chip to the MEMSdevice.
 18. The method of claim 16, further comprising creating openingsin the glass substrate, wherein releasing the first and secondsacrificial layers comprises releasing the first and second sacrificiallayers through the openings.
 19. The method of claim 16, whereindepositing the membrane mirror comprises: depositing a bottom mirrorlayer; depositing a dielectric layer; and depositing a top mirror layer.20. The method of claim 16, wherein the electrode is a transparentelectrode.